^Note|Restricted attr() so that declared type and fallback type must match when it's used as a component value.|

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^Note|Restricted attr() so that declared type and fallback type must match when it's used as a component value. ​See [[http://​dev.w3.org/​csswg/​css3-values/#​attr-notation|edits]] ("The attr() expression is only valid if"​) ​|